scholarly journals ENSAIOS EM VIGAS DE ALVENARIA SUBMETIDAS À FLEXÃO SIMPLES

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Maria das Graças Duarte de Oliveira ◽  
Edgar Bacarji ◽  
Gilson Natal Guimaraes
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Cross Section ◽  
Shear Failure ◽  
Flexural Behavior ◽  
Longitudinal Reinforcement ◽  
Code Of Practice ◽  
Concrete Masonry ◽  
Concrete Blocks ◽  
The Cross

RESUMO: Foi realizado um estudo experimental de vigas de alvenaria de concreto submetidas à flexão simples e as variáveis usadas foram a altura da seção transversal e a distribuição das barras da armadura longitudinal. Foram confeccionadas nove vigas com blocos e canaletas de concreto de resistência característica a compressão de 13 MPa. A altura da seção transversal foi definida pela quantidade de fiadas de blocos: uma, duas e três fiadas. As barras de aço da armadura longitudinal foram distribuídas na seção transversal, mantendo constante a taxa de armadura. Foram moldadas três vigas apenas com canaletas e sem estribos, pois seu uso é muito comum na região de Goiânia, GO. Os resultados obtidos foram confrontados com valores encontrados utilizando as recomendações de dimensionamento da norma NBR15961-1 (2011).  De modo geral, as vigas com estribos e com armadura longitudinal distribuídas nas diversas fiadas tiveram desempenho melhor, sendo estas mais dúcteis e mais seguras que as vigas apenas com canaletas e sem estribos. Essas vigas com estribos romperam por flexão e as cargas de ruptura excederam os valores calculados conforme as recomendações de norma. Já as vigas sem estribos romperam por cisalhamento com cargas de ruptura menor ou igual ao recomendado por norma. Este estudo mostra que não devem ser utilizadas vigas de alvenaria sem estribos. ABSTRACT: An experimental study of the flexural behavior of concrete masonry beams subjected to flexure was done and the variables used were the height of the cross section and the distribution of the longitudinal reinforcement along the layers of blocks. Nine concrete masonry beams were cast and tested with concrete blocks of 13 MPa compressive strength. The height of the cross section was defined by the number of blocks: one, two or three layers. The steel longitudinal reinforcement was distributed along the cross section, such that the steel arrangement gave the same steel reinforcing ratio for all beams. Three beams with lintels only and without stirrups were cast since its use if very common in the region of Goiania, GO. Results obtained were compared to those values obtained using recommendations prescribed in Brazilian code of practice NBR 15961-1 (2011). In general, beams with stirrups and with longitudinal reinforcement distributed along the height of the cross section had better performance, were more ductile and safer than beams without stirrups. These beams failed in flexure and ultimate loads were above those calculated using code recommendations. Beams without stirrups had a shear failure with ultimate loads lower than recommended by the code. This study shows that beams without stirrups should not be used.

scholarly journals EXPERIMENTAL STUDY ON RC BEAM SPECIMENS WITH CFRP ROD/MESH EMBEDDED AND INCREASING THICKNESS OF THE CROSS SECTION

2020 ◽  
Vol 73 (1) ◽  
pp. 348-354
Author(s):  
Shohei UEMURA ◽  
Kiyoshi MURAKAMI ◽  
Ayumi SATOH ◽  
Seiichiro YAMAUCHI
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Rc Beam ◽  
The Cross

Biaxial bending of cold-formed angle members

1984 ◽  
Vol 11 (4) ◽  
pp. 933-942 ◽  
Author(s):  
Murty K. S. Madugula ◽  
Sujit K. Ray
Keyword(s):  
Exact Solution ◽  
Compressive Strength ◽  
Computer Program ◽  
Cross Section ◽  
Simultaneous Equations ◽  
Biaxial Bending ◽  
Total Stress ◽  
The Cross ◽  
The Galerkin Method ◽  
Shear Centre

Theoretical load–deflection relationships for cold-formed angles under biaxial bending using the Galerkin method are presented. The computational difficulties encountered in the exact solution of differential equations of equilibrium involving 12 unknown constants in 12 simultaneous equations are pointed out. A computer program for pinned-end boundary conditions was developed to estimate the deflection components of the shear centre, to calculate the total stress at various points in the cross section, and to predict the ultimate strength of the cold-formed angle sections connected by one leg. Failure is assumed to have occurred when the total stress at any point on the cross section reaches the value of yield stress, compressive or tensile, or when there is a change of sign for at least one of the deflection components. A table giving the ultimate compressive strength of two commonly used cold-formed angles for various gauge distances is included. The theoretical load–deflection curves are compared with experimental results and typical curves for three test specimens are also presented.

scholarly journals Compressive strength of masonry constructed with high strength concrete blocks

2017 ◽  
Vol 10 (6) ◽  
pp. 1273-1319 ◽  
Author(s):  
E. S. FORTES ◽  
G. A. PARSEKIAN ◽  
J. S. CAMACHO ◽  
F. S. FONSECA
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Strain Curve ◽  
High Strength ◽  
Masonry Walls ◽  
Strength Ratio ◽  
Stress Strain Curve ◽  
Strength Concrete ◽  
Concrete Masonry ◽  
Concrete Blocks

Abstract Although the use of high strength concrete blocks for the construction of tall buildings is becoming common in Brazil, their mechanical properties and behavior are not fully understood. The literature shows a gap in experimental studies with the use of high strength concrete blocks, i.e., those with compressive strength greater than 16 MPa. The work presented herein was conducted in order to study the behavior of high strength structural masonry. Therefore, the compressive strength and modulus of elasticity of concrete block walls tested under axial load were assessed. The specimens included grouted and ungrouted walls and walls with a mid-height bond beam; ungrouted walls were constructed with face-shell and full mortar bedding. The walls were built and tested in the laboratory of CESP and in the Structures Laboratory of the UNESP Civil Engineering Department in Ilha Solteira (NEPAE). Concrete blocks with nominal compressive strength of 16 (B1), 24 (B2) and 30 (B3) MPa were used. Ungrouted masonry walls had a height of 220 cm and a width of 120 cm while grouted masonry walls had a height of 220 cm and a width of 80 cm. Traditional Portland cement, sand and lime mortar was used. The testing program included 36 blocks, 18 prisms, 9 ungrouted walls (6 with face-shell mortar bedding and 3 with full mortar bedding), 9 grouted masonry walls, and 12 ungrouted walls with a bond beam at mid-height. The experimental results were used to determine the compressive strength ratio between masonry units, prisms and masonry walls. The analyses included assessing the cracking pattern, the mode of failure and the stress-strain curve of the masonry walls. Tests results indicate that the prism-to-unit strength ratio varies according to the block strength; that face-shell mortar bedding is suitable for high strength concrete masonry; and that 20% resistance decrease for face-shell mortar bedding when compared with full mortar bedding is a conservative consideration. The results also show that using a bond beam at the mid-height of the wall does not lead to a compressive strength decreased but it changes the failure mode and the shape of the stress-strain curve. In addition, the results show that estimating E = 800 fp is conservative for ungrouted masonry walls but reasonably accurate for grouted masonry walls and that there is no reason to limit the value of E to a maximum value of 16 GPa. Furthermore, the results show that, for design purposes, a wall-to-prism strength ratio value of 0.7 may be used for high strength concrete masonry.

scholarly journals Experimental study of the influence of the cross section of the lonnago joint on the size of the pelvis

2020 ◽  
Vol 8 (1) ◽  
pp. 13-22
Author(s):  
E. B. Dimant
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Anatomical Studies ◽  
The Cross

Practice outpaced theory on the issue of symphysiotomy. Until now, this operation has not been scientifically sufficiently substantiated due to the fragmentary, incomplete and inaccurate anatomical studies. There is still a lack of accurate pelvic measurements. Fully aware of the need and importance of filling this gap, I willingly took on the proposal and under the guidance of prof. D.O. Ott for real research.

scholarly journals Study of the Production Cross-Sections of the Neutron-rich 184Ta and 186Ta

2021 ◽  
Vol 9 (1) ◽  
pp. 25-29
Author(s):  
Susshma Nagarajan ◽  
Deepa Seetharaman ◽  
Gowrishankar Ramadurai
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Cross Section ◽  
Cross Sections ◽  
Good Yield ◽  
Production Cross ◽  
Effective Synthesis ◽  
The Cross

Synthesizing nuclei through reactions that produce a reasonable yield is important for the experimental study of neutron-rich nuclei. In this study, the cross-section values of 184Ta and 186Ta nuclei in various experiments were reviewed and analysed. The experimental data of (n, p), (p, x) and (n, α) reactions were compared to identify the best reaction to produce these nuclei for further study. Our study shows that (n, p) reactions on natural Tungsten targets are the most feasible reactions with a good yield of the neutron-rich Tantalum isotopes. New reactions have been proposed for the effective synthesis of 184Ta and 186Ta using tritium beams on Hafnium targets. The cross-section values of the proposed reactions were calculated by PACE4 software simulations.

Combined Bending and Compression of a Pressurized Circular Cylindrical Membrane Column

1965 ◽  
Vol 87 (3) ◽  
pp. 372-378
Author(s):  
W. E. Jahsman
Keyword(s):  
Compressive Strength ◽  
Cross Section ◽  
Compressive Load ◽  
Circular Cross Section ◽  
Bending Moment ◽  
Maximum Load ◽  
Bending Moments ◽  
Lateral Deflection ◽  
The Cross

Load-lateral deflection curves are developed for a pressurized tube of circular cross section under combined bending and compression. The tube walls are assumed to have negligible compressive strength so that wrinkling develops if the stress tends to become negative. It is found that for a given bending moment, the load increases monotonically with deflection until a maximum is reached beyond which the load decreases with increasing deflection. An interaction curve of the maximum load versus bending moment shows that the presence of only a small amount of bending significantly decreases the maximum compressive load below the classical Euler load. Conversely, for bending moments which produce almost complete wrinkling of the cross section, only very small amounts of compressive load can be supported.

scholarly journals Gravity wave amplification and phase crest re-organization over a shoal

2011 ◽  
Vol 11 (3) ◽  
pp. 789-796 ◽  
Author(s):  
N. Jarry ◽  
V. Rey ◽  
F. Gouaud ◽  
D. Lajoie
Keyword(s):  
Experimental Study ◽  
Surface Wave ◽  
Cross Section ◽  
Phase Evolution ◽  
Wave Direction ◽  
Wave Amplification ◽  
Wave Measurements ◽  
The Cross ◽  
Diffraction Effects ◽  
Wave Properties

Abstract. In this experimental work, both wave amplification and phase evolution, due to a submerged mound, are studied. In addition to the classical surface wave measurements, the experimental study takes advantage of photographs that underline crest re-organization above and down-wave the shoal. In particular, together with wave amplification up to more than twice the incident wave, a wave steepening is observed in certain conditions in both the wave direction and in the cross-section. Due to a phase crest separation downstream of the shoal, steepening in the cross-shore direction is enhanced (up to 30% above the steepening along the main direction of propagation). Physical aspects are discussed through the analysis of the diffraction effects on the wave properties.

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